This invention relates to endotracheal airway devices and, more particularly, to a cuffed endotracheal tube and method.
Conventionally, the cuff of a single cuffed endotracheal tube is inflated with air following insertion of the device into the middle portion of the trachea of a patient to achieve an air-tight seal of the space between the tube and surrounding tracheal wall. As such, the single cuffed endotracheal tube has been routinely employed for many decades to prevent upper airway obstruction and to facilitate artificial respiration of the unconscious or anesthesized patient. However, recent investigations have disclosed several defects in the design of conventional single cuffed endotracheal tubes.
Among these defects are, firstly, the failure to prevent secretions from accumulating in the upper trachea; secondly, the abrading of the vocal cords as a result of to and fro motion caused by respiration; and thirdly, the injury to the cilia and surface membranes of the mid-trachea caused by intra-cuff sealing pressure upon the tracheal wall.
While all of these defects are significant, the possibly injury to the cilia and surface membranes of the mid-trachea is perhaps most damaging. The degree of such injury is proportional to the magnitude of lateral wall-cuff pressure in excess of 15 centimeters of water and to the duration such pressure is applied. Conventionally, the single cuffed endotracheal tube has been used with the cuff inflated in place in the mid-trachea several centimeters below the larynx where compression of the ciliated endothelium of the trachea causes the injury.
Conventional single cuffed endotracheal tubes produce a non-leak seal in the mid-trachea at pressures which occlude the blood perfusion of the tracheal mucosa after a period of time producing tissue necrosis without sufficient assurances against bronchial intubation and inadvertent extubation. This also holds true for alternately inflated midtracheal double cuff structures forming a part of the prior art. In contrast, the present invention provides a pair of enlargements at least one of which is an inelastic inflatable-deflatable cuff, anchoring the tube on either side of the larynx at pressures lower than those sufficient to cause injury in a manner preventing bronchial intubation and inadvertent extubation.
Another problem arising from prevailing practices of tracheal intubation is the failure of the conventional single cuffed endotracheal tube to prevent secretions from passing through an unprotected space between the vocal cords and the tube. The result is accumulation of a ring of contaminated material in the upper trachea above the single inflated cuff which enters the lung when the cuff is deflated at extubation and which can be even more immediate with alternately inflated mid-tracheal double cuff structures. During intubation, this residue or ring of infected secretions trickles into the larynx and becomes entrapped above the single inflated cuff until subsequent extubation allows the ring of secretions to enter the mid-trachea where injured cilia fail to protect the lung.
The normal protective mechanism by which the cilia carry the secretions upward in the respiratory tree until reflex coughing results in their removal fail to operate. My invention eliminates such aspiration by virtue of placing an inelastic inflatable-deflatable cuff above the larynx to keep the upper airway secretions from entering the laryngeal area. After insertion and initial inflation, the cuff rests above the larynx thereby preventing exposure of the larynx and trachea to contamination.
By leaving inflated the cuff described herein, oral secretions may be removed by suction catheter with both the larynx and trachea protected. Thus, the present invention is superior to the conventional single cuffed endotracheal tubes as well as the alternately inflated mid-tracheal double cuff structure is at least four important features, as herein embodied, including (1) a positive means of anchoring a pair of enlargements on either side of the vocal cords thereby preventing tube motion, accidental extubation, or further penetration of the tube into a bronchus, (2) the option of zero sealing pressure below the vocal cords, (3) the prevention of secretions from traveling into the area of the upper trachea or larynx where they might cause permanent injury, and (4) a method of using a cuffed endotracheal tube providing a positive external indication by reason of the location of the enlargements on either side of the glottis. While the prior art has attempted to deal with the problems associated with endotracheal airway devices in various ways and with various degrees of success, the present invention represents an important advance in the art.